#!/bin/bash
# Program:
#	Try do calcuate 1+2+..+${your_input}
# History:
# 2015/11/17	Leonardo	First release
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH

read -p "Please input a number, I will count for 1+2+...+your_input: " nu

s=0;
for((i=1;i<=$nu;i=i+1))
do
	s=$(($s+$i))
done
echo "The result of '1+2+3+...+$nu' is ==> $s"

